Republican presidential candidates and outside groups which support them have spent $38.7 million on political advertising since last fall, according to data acquired by TIME.

In the political mud pit of South Carolina, whose Jan. 21 primary is next on the calendar, candidates and their super PACs have already dropped more than $9 million so far this cycle. The top three spenders in South Carolina have all been super PACs, led by Restore Our Future, a Mitt Romney–allied group, at $2.1 million. Texas Governor Rick Perry’s super PAC, Make Us Great Again, has pumped $1.77 million into the Palmetto State so far, and Winning Our Future PAC, which backs Newt Gingrich, trails close behind at $1.6 million. Those sums are poised to swell quickly, with both Perry and Gingrich planning to savage Romney in South Carolina in an effort to stymie the front runner’s momentum.

The new figures provide a stark picture of the impact superior financing can have on a candidate’s fortunes. Romney’s campaign and super PAC have dwarfed his rivals in media buys, pouring nearly $15 million since November into radio and television time. Perry, the second-highest spender, has funneled some $9.7 million into ads promoting his campaign. Buoyed by small-dollar donors, Ron Paul checks in third with nearly $5 million in ad spending. Newt Gingrich and his allies have forked over $3.1 million for ads, a million more than Jon Huntsman. At $1.18 million, Rick Santorum, who battled Romney to a virtual draw in Iowa on a shoestring budget, has shelled out the least for paid media among the GOP field.

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The new data confirms that Super PACS — independent-expenditure committees that can take large, million-dollar donations to promote candidates — have in several cases spent more on ads than the campaigns themselves. Restore Our Future PAC has been the largest single ad buyer so far this cycle, shelling out just under $9 million since the beginning of December. Perry’s Make Us Great Again has spent $3.4 million, more than the total tabs rung up by Gingrich, Huntsman and Santorum. Super PAC spending has accounted for nearly half of all paid media on broadcast networks, cable TV and radio since the fall. Their ability to boost allied candidates or blanket opponents with negative ads has played a crucial role in shaping the contours of the race, even though they are prohibited from coordinating with or funneling money directly to campaigns.

The busiest theater in the war so far has been Iowa, home to the nation’s first caucus contest and the state where some candidates spent a year. Candidates, allied organizations and opposing groups lavished $16.5 million in ad buys on the Hawkeye State, led by the Perry campaign, which doled out $4.32 million, plus $1.64 million from his super PAC, in exchange for just 12,604 votes — a rate of $495 apiece. Romney, who won the caucuses by a razor-thin margin, was the second-highest spender, shelling out nearly $4.2 million between his campaign and Super PAC. Much of that sum went toward burying Gingrich under an avalanche of blistering ads. Paul, who finished third, spent $2.76 million. Santorum fought to a hard-earned tie on the cheap; his Super PAC — the Red, White and Blue Fund — footed almost his entire $552,000 ad bill.

In addition to the top three super PACs dominating ad spending in South Carolina, Santorum has made his first sizable ad buys for broadcast time in Myrtle Beach, Columbia and Charleston. Perry, Gingrich and Romney have all spent heavily to buy 1,500 to 4,400 gross rating points in Columbia, Greenville, Myrtle Beach and Charleston. The $9 million lavished on the state is likely to grow fast, as Santorum books time with the $3 million in donations that flowed in during the week after his Iowa surge, and Gingrich and Perry double down on their attacks casting Romney’s tenure at Bain Capital as responsible for scores of lost jobs. Gingrich’s super PAC, backed by the largesse of billionaire casino magnate Sheldon Adelson, has signaled its intention to buy $3.4 million in ad time.

Romney is the only Republican so far to purchase ads in Florida, whose critical Jan. 31 primary requires competing in several major media markets, making it prohibitively expensive for underfunded candidates. Romney’s campaign and super PAC have spent $6.1 million so far in the Sunshine State. By contrast, Ron Paul has opted to skip Florida altogether to pursue a strategy of cornering smaller, cheaper states like Nevada, where he recently became the first candidate to purchase air time.

This data was compiled for TIME as of Jan. 6 by Smart Media Group. It tracks ad purchases made on broadcast networks, cable and radio.